1. Field of the Invention
The present invention is directed to a device for winding and unwinding at least two lines and an apparatus employing such a device, the lines connecting an apparatus part to electrically operated devices of the apparatus that can be dislocated relative to the apparatus part.
2. Description of the Prior Art
German PS 40 19 513 discloses a device with a rotatable drum arrangement for winding and unwinding a line. The drum arrangement has an outer, hollow-cylindrical drum that is rotatably seated around an inner hollow-cylindrical drum that is stationary relative to the outer drum. The outer drum accepts the line in the form of a ribbon cable and a rope. The ribbon cable and the rope can be wound and unwound in opposite directions on different regions of the outer drum. The device is arranged in an apparatus part of an apparatus that has a second apparatus part with electrically operated devices that can be adjusted relative to the first apparatus part. The ribbon cable electrically connects the two apparatus parts to one another, the ribbon cable and the rope respectively having ends secured to different ends of the second apparatus part. When a tensile force is exerted on the ribbon cable by moving the two apparatus parts relative to one another, the ribbon cable is unwound from the rotatable drum and the rope is wound on the rotatable drum and, given exertion of a tensile force on the rope due to opposite movement of the two apparatus parts relative to one another, the rope is unwound from the rotatable drum and the ribbon cable is wound onto the rotatable drum. A spring via which the rope end is secured to the second apparatus part serves the purpose of exerting a constant tensile force on the rope, and thus on the ribbon cable, so that this is wound onto the drum with a slight pre-stress.
The winding and unwinding of the ribbon cable, which, can have its other end connected to an energy supply and to a control and signal processing unit, onto the rotatable drum is possible only because a portion of the ribbon cable is wound in a helix around the inner drum. The respective surfaces of the two hollow-cylindrical drums have an opening through which the ribbon cable is conducted. The ribbon cable is initially conducted via a lateral opening of the inner drum through the opening of the surface of the inner drum in the region between the drums, is wound as a helix around the inner drum, and is conducted toward the exterior through the opening of the surface of the outer drum. The portion of the ribbon cable that is located between the drums has its section ends secured such to the inner and outer drum so that, given rotation of the outer drum around the inner drum, the ribbon cable is wound onto or is unwound from the surface of the outer drum and, when the ribbon cable is wound onto or unwound from the outer drum, the helix formed by the region of the ribbon cable lying between the drums is constricted or expands in the direction toward the surface of the inner drum.
The known device is only suitable for the acceptance of a ribbon cable that can be reliably wound onto or unwound from the outer drum, i.e. without forming loops. This is a disadvantage because ribbon cables are expensive and have a high space requirement when being wound onto a drum.
German PS 196 51 960 discloses an apparatus having a device for the transmission of electrical energy and/or of signals from one apparatus part to electrical devices that can be displaced relative to the apparatus part, using round lines. The device has a rotatable drum onto which another line is wound when one line is unwound.
A disadvantage of this known device is that the drum, which is composed of an outer and an inner, hollow-cylindrical drum with the outer drum rotating around the stationary inner drum, does not offer adequate space for the acceptance of the lines. Particularly the space between the outer and the inner drum wherein, as described above, the lines are wound in a helix around the inner drum, is not adequate for accepting lines having larger line diameters and given the condition of not having to implement the drums too large.